Single use syringe

Abstract

A single use syringe has a needle which is biased back into the barrel but which is prevented from doing so by a holding means which has an outer part and an inner part which are connected together by a frangible portion. The needle is held by the inner part. When the plunger is pushed towards the front of the barrel, it contacts the outer part and pushes it forwardly which stretches the frangible portion until it bursts. When the frangible portion breaks, the inner portion containing the needle is released and can shoot back into a hollow portion in the plunger through the frangible portion of the plunger head.

Description

FIELD OF THE INVENTION[0001]This invention relates to a single use single use syringe and particularly relates to a single use syringe where the syringe needle is biased into the syringe body after use.BACKGROUND ART[0002]Single use syringes are required to reduce the risk of infection caused by needle sharing. Many types of single use syringes are known.[0003]A disadvantage with most of these known syringes is the complexity of manufacture and the rather large number of parts which are required in order to allow the syringe to be used effectively.[0004]This invention is directed to a single use syringe of the type which has a needle which can be shot into a hollow plunger stem upon completion of the plunger stroke to prevent the needle from being use again. In particular, the invention is directed to a relatively simply insert which is fitted into the needle and which can securely hold the needle in its use position but which can release the needle to shoot the needle back into the...

AI Technical Summary

Benefits of technology

"The present invention is a single use syringe with a spring biased needle that can shot back into the hollow plunger stem after use. The needle is held in place by a holding means with a frangible portion that can be broken to release the needle. The frangible portion is broken by a stretching action which bursts the frangible portion, rather than a cutting action which can cause unreliable results. The syringe is simple in design, can be easily manufactured, and can be made from inexpensive components. The invention provides a safer and more reliable alternative to conventional syringes."

Problems solved by technology

A disadvantage with most of these known syringes is the complexity of manufacture and the rather large number of parts which are required in order to allow the syringe to be used effectively.

One type of syringe which shoots the needle back into the syringe body is extremely complicated and has up to 16 parts which must be assembled to form the finished syringe.

Some of the parts need to be glued as the parts are too small for injection or die moulding.

This known syringe is also restricted to volumes of larger than 3 ml as the various parts cannot be made to fit smaller syringes.

Another disadvantage with known syringes of this type is the inability to easily and readily injection mould the various components.

In practice, it is found that such a barrel is extremely difficult to mould and is virtually impossible to injection mould.

Thus, this type of syringe cannot be manufactured cheaply.

It is believed that this type of arrangement would not be particularly reliable as it does not include a more reliable frangible portion which is broken to allow the spring biased needle to shoot back into the plunger stem.

This type of syringe is of course fairly limited in use to circumstances where suction can be provided.

It is found that attempting to cut a cuttable member to release a spring biased needle is not always reliable and does not always work.

This arrangement requires a needle having a special design (containing an enlargement) which means that conventional needles cannot be used.

This arrangement requires a sliding frictional grip to hold the two-part together which is considered quite risky and requires careful manufacture.

The use of an elongate body in a needle holder makes this arrangement difficult for use small and confined spaces.

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